Non-access stratum based access method and terminal supporting the same

ABSTRACT

A non-access stratum based access method and a terminal supporting the same. The terminal receives an Internet protocol (IP) address allocated from a first gateway included in a non-3 rd  generation partnership project (3GPP) access network. In addition, the terminal applies a non-access stratum (NAS) protocol to a first device managing mobility of the terminal through the IP address.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication Nos. 10-2016-0043554 and 10-2017-0038743, filed in theKorean Intellectual Property Office on Apr. 8, 2016 and Mar. 27, 2017,respectively, the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a non-access stratum based accessmethod and a terminal supporting the same.

2. Description of Related Art

A 3^(rd) generation partnership project (3GPP) standard provides astructure standard for interworking of a long term evolution (LTE)network and a non-3GPP access network (for example, wireless broadband(WiBro), wireless fidelity (WiFi), or the like). As technology ofoffloading WiFi to the LTE network using an LTE network infrastructure,there are an evolved packet data network (PDN) gateway (ePDG) standard(3GPP Rel-8) and a trusted wireless local area network (WLAN) accessgateway (TWAG) standard (3GPP Rel-11). In addition, there is an Internetprotocol (IP) flow mobility (IFOM) standard (3GPP Rel-10) capable ofsimultaneously using the LTE and the WiFi.

In the ePDG standard, an ePDG is added for the purpose of interworkingbetween a 3GPP core network and a WiFi access network. A terminalperforms an authentication procedure such as extensible authenticationprotocol-authentication and key agreement (EAP-AKA), or the like, on theWiFi network, and then receives an IP address allocated from the ePDG tocreate an Internet protocol security (IPSec) tunnel with the ePDG. Inaddition, the ePDG creates a generic routing encapsulation (GRE) tunnelwith a PDN gateway (P-GW) through a proxy mobile IPv6 (PMIPv6) protocol.

In a network structure of the TWAG standard for removing dependency ofthe terminal and interworking a WLAN with the LTE, the terminal performsonly a WLAN access function using a 802.1X authentication procedure. Inaddition, the TWAG performs Internet key exchange (IKE)/IPsec connectionwith the WiFi network, and may create a GRE tunnel with the P-GW.

The IFOM standard is technology capable of transmitting data of a singleaccess point name (APN) service traffic to the LTE and the WLAN. In thecase in which the terminal interworks with the ePDG or the TWAG toperform an access through the WLAN, a dual-stack mobile IPv6 (DSMIPv6)signaling and IP-in-IP tunnel is created through encrypted connection ofInternet key exchange 2 (IKEv2)/IPsec.

According to the methods according to the related art described above,in the case in which the 3GPP LTE network and the non-3GPP accessnetwork interwork with each other, a general packet radio service (GPRS)tunneling protocol (GTP)-C/U or PMIPv6/GRE, DSMIPv6/IP-in-IP tunnelbased mobility function is applied to the non-3GPP access networkinstead of a mobility function of the LTE network. Therefore, there is aproblem that it is difficult to provide seamless handover.

In the LTE network, a non-access stratum (NAS), which is a protocolstack between the terminal and a core network, performs sessionmanagement for communication and mobility management of the terminal.Currently, the terminal supporting the NAS may receive the seamlesshandover through the LTE network, but an NAS access is not supported tothe terminal in the non-3GPP access network such as the WiFi.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to provide a non-accessstratum based access method and a terminal supporting the same havingadvantages of providing seamless handover even in various accessnetworks.

An exemplary embodiment of the present invention provides a method foraccessing a core network through a non-3^(rd) generation partnershipproject (3GPP) access network by a terminal. The method may include:receiving an Internet protocol (IP) address allocated from a firstgateway included in the non-3GPP access network; and applying anon-access stratum (NAS) protocol to a first device managing mobility ofthe terminal through the IP address.

The receiving of the IP address allocated from the first gateway mayinclude receiving a temporary IP address allocated from the firstgateway.

The receiving of the IP address allocated from the first gateway mayinclude creating an Internet protocol security (IPSec) with the firstgateway.

The first gateway and the first device may be connected to each other.

The non-3GPP access network may be a wireless local area network (WLAN).

The non-3GPP access network may be an untrusted non-3GPP access network.

The receiving of the temporary IP address allocated from the firstgateway may include receiving the temporary IP address allocated fromthe first gateway through an IPv6 auto-configuration method or a dynamichost configuration protocol (DHCP) method.

The creating of the IPSec tunnel may include: performing an Internet keyexchange (IKE) security association (SA) process together with the firstgateway; and performing an IPSec security association (SA) processtogether with the first gateway.

The applying of the NAS protocol may include: receiving a security modecommand message from the first gateway through the IP address; andtransmitting a security mode complete message to the first gatewaythrough the IP address.

The applying of the NAS protocol may further include: receiving anattach accept message from the first gateway through the IP address.

Another exemplary embodiment of the present invention provides a methodfor accessing a core network through an Ethernet network by a terminal,including: performing media access control (MAC) communication with afirst gateway included in the Ethernet network; and applying an NASprotocol to a first device supporting mobility of the terminal, throughthe MAC communication.

The first gateway and the first device may be connected to each other.

The applying of the NAS protocol may include applying the NAS protocolto the first device by adding Ether_Type to an Ethernet frame.

The applying of the NAS protocol may include applying the NAS protocolto the first device by using a specific MAC address.

An NAS stratum may be positioned on an MAC stratum in the terminal, andan NAS stratum may be positioned on an IP stratum in the first device.

Yet another exemplary embodiment of the present invention provides aterminal initially accessing a core network through a non-3GPP accessnetwork. The terminal may include a processor performing a control toreceive an IP address allocated from a first gateway included in thenon-3GPP access network and performing a control to apply an NASprotocol to a first device managing mobility of the terminal through theIP address; and a radio frequency (RF) module transmitting and receivinga message corresponding to the NAS protocol.

The IP address may be a temporary IP address allocated from the firstgateway.

The IP address may be a temporary IP address allocated from the firstgateway by creating an IPSec with the first gateway.

The first gateway and the first device may be directly connected to eachother.

The processor may configure an NAS stratum to be positioned on an IPstratum.

According to an exemplary embodiment of the present invention, the NASprotocol is applied to the non-3GPP access network, thereby making itpossible to provide seamless handover.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a network structure according to an exemplaryembodiment of the present invention.

FIG. 2 is a view showing a non-access stratum (NAS) based access methodaccording to an exemplary embodiment of the present invention.

FIG. 3 is a view showing a protocol stack of a control plane forapplying the NAS based access method according to an exemplaryembodiment of the present invention.

FIG. 4 is a view showing an NAS based access method according to anotherexemplary embodiment of the present invention.

FIG. 5 is a view showing a protocol stack of a control plane forapplying the NAS based access method according to another exemplaryembodiment of the present invention.

FIG. 6 is a view showing a protocol stack of a data plane for applyingthe NAS based access method according to an exemplary embodiment of thepresent invention.

FIG. 7 is a view showing another example of a protocol stack of acontrol plane for applying the NAS based access method according to anexemplary embodiment of the present invention.

FIG. 8 is a view showing a protocol stack of a control plane forapplying an NAS based access method according to yet another exemplaryembodiment of the present invention.

FIG. 9 is a view showing a protocol stack of a data plane for applyingthe NAS based access method according to yet another exemplaryembodiment of the present invention.

FIG. 10 is a view showing a terminal according to an exemplaryembodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following detailed description, only certain exemplaryembodiments of the present invention have been shown and described,simply by way of illustration. As those skilled in the art wouldrealize, the described embodiments may be modified in various differentways, all without departing from the spirit or scope of the presentinvention. Accordingly, the drawings and description are to be regardedas illustrative in nature and not restrictive. Like reference numeralsdesignate like elements throughout the specification.

Throughout the present specification, a terminal may indicate a mobileterminal (MT), a mobile station (MS), an advanced mobile station (AMS),a high reliability mobile station (HR-MS), a subscriber station (SS), aportable subscriber station (PSS), an access terminal (AT), a userequipment (UE), or the like, and may include all or some of thefunctions of the terminal, the MT, the AMS, the HR-MS, the SS, the PSS,the AT, the UE, or the like.

In addition, a base station (BS) may indicate an advanced base station(ABS), a high reliability base station (HR-BS), a nodeB, an evolvednodeB (eNodeB), a base transceiver station (BTS), a mobile multihoprelay (MMR)-BS, a relay station (RS) serving as a base station, a highreliability relay station (HR-RS) serving as a base station, and thelike, and may include all or some of the functions of the base station,the ABS, the nodeB, the eNodeB, the BTS, the MMR-BS, the RS, the HR-RS,and the like.

FIG. 1 is a view showing a network structure according to an exemplaryembodiment of the present invention.

As shown in FIG. 1, the network structure according to an exemplaryembodiment of the present invention includes a terminal 100, a basestation 110, a mobility management entity (MME) 120, a home subscriberserver (HSS) 130, a packet data network (PDN) gateway (P-GW) 140, anaccess point (AP) 150, and an evolved PDN gateway (ePDG) 160.

In FIG. 1, the base station 110 forms a 3^(rd) generation partnershipproject (3GPP) access network N1, and the AP 150 and the ePDG 160 form awireless fidelity (WiFi) access network N2. In addition, the MME 120,the HSS 130, and the P-GW 140 form a core network N3. Here, although theWiFi access network (that is, a wireless local area network (WLAN)) isillustrated as an example of a non-3GPP access network, it may bereplaced by other network such as a wired network. Here, the AP 150 maybe a mobile type AP or a fixed type AP.

The MME 120 according to an exemplary embodiment of the presentinvention, which is an entity managing access and mobility of theterminal 100, and is an end point of non-access stratum (NAS) signaling.Therefore, the MME 120 enables the terminal 100 to access the corenetwork providing mobility through the 3GPP or non-3GPP access network.In addition, the MME 120 establishes NAS signaling connection to performmobility management. The MME 120 may be replaced by a term ‘access andmobility function (AMF)’.

The ePDG 160 is an entity for interworking between the non-3GPP accessnetwork (for example, the WLAN) and the core network N3. The terminal100 may access the core network N3 through the ePDG 160 in the non-3GPPaccess network. The ePDG 160 may allow the terminal 100 to transmit anNAS protocol to the core network N3. In order to provide the function asdescribed above, the ePDG 160 is directly connected to the MME 120, asshown in FIG. 1. The ePDG 160 may be replaced by a term ‘non-3GPPinterworking function (N3IWF)’.

The P-GW 140 is connected to each of the base station 110, the MME 120,and the ePDG 160 and is also connected to a data network (not shown).

The terminal 100 according to an exemplary embodiment of the presentinvention supports the NAS protocol. The NAS protocol as described aboveis applied to the non-3GPP access network N2 as well as the 3GPP accessnetwork N1. Therefore, seamless handover may be provided regardless ofan access network. That is, in an access method according to anexemplary embodiment of the present invention, the NAS protocol is alsoapplied to the non-3GPP access network N2, thereby making it possible toprovide mobility. Such an access method according to an exemplaryembodiment of the present invention will be described below in detail.

FIG. 2 is a view showing a non-access stratum (NAS) based access methodaccording to an exemplary embodiment of the present invention. In moredetail, FIG. 2 shows procedures of applying the NAS protocol to the WiFiaccess network (the non-3GPP access network) to allow the terminal 100to initially access the core network.

First, the terminal 100 performs communication with the ePDG 160 toreceive a temporary Internet protocol (IP) address allocated thereto(S210). That is, in order to transfer an NAS message, IP communicationis performed between the terminal 100 and the ePDG 160. In order toperform the IP communication, the terminal 100 receives the configuredtemporary IP address. As a method for configuring the temporary IPaddress, two methods may be used. A first method is a IPv6auto-configuration method, and a second method is a dynamic hostconfiguration protocol (DHCP) method.

In the IPv6 auto-configuration method, a stateless IPv6 address isconfigured. The terminal 100 transmits a router solicitation (RS)message to the ePDG 160 to inform the ePDG 160 of a network access. TheePDG 160 receiving the RS message configures the stateless IPv6 addressas a network prefix value in a router advertisement (RA) message, andtransmits the RA message to the terminal 100.

In the DHCP method, an IPv4 address value or an IPv6 address value isarbitrarily configured. The terminal 100 access the network to transmita DHCP request message to the ePDG 160. The ePDG 160 receiving the DHCPrequest message allocates a temporary IP address, allows the allocatedtemporary IP address to be included in a DHCP request message, andtransmits the DHCP request message including the allocated temporary IPaddress to the terminal 100.

The temporary IP address allocated as described above is used by a user(that is, a terminal) authenticated through an authentication procedure,and communication is not allowed with respect to a user IP address thatis not authenticated. Meanwhile, the temporary IP address allocated inS210 is different from an IP address allocated to the terminal 100 by aP-GW 140 described below.

In the NAS based access method according to an exemplary embodiment ofthe present invention, the NAS protocol is applied using the temporaryIP address allocated in S210. This will be described in detail below.

The terminal 100 transmits an attach request message to the MME for aninitial access (S220).

The MME 120 receiving the attach request message requests the HSS 130 totransmit an authentication information request message for subscriberauthentication (S221).

The HSS 130 receiving the authentication information request messagecreates an authentication vector for the user (that is, the terminal),allows the authentication vector to be included in an authenticationinformation response message, and transmits the authenticationinformation response message including the authentication vector to theMME 120 (S222).

The MME 120 obtaining the authentication vector for the user allowsrelated information to be included in an authentication request messageand transmits the authentication request message including the relatedinformation to the terminal 100 (S223), in order for the terminal 100 tocreate the authentication vector and perform network authentication.Here, the related information may be a partial value of theauthentication vector.

The terminal 100 performs the network authentication using the relatedinformation included in the authentication request message, and createsthe authentication vector of the terminal 100. The terminal 100transmits the created authentication vector of the terminal 100 to theMME 120 through an authentication response message (S224). The MME 120may authenticate the user using the received authentication responsemessage.

When subscriber authentication succeeds, an NAS security setup procedureis performed between the MME 120 and the terminal 100. The MME 120transmits a security mode command message to the terminal 100 (S225).The terminal 100 receiving the security mode command message creates anNSA security key, and transmits a security mode complete message to theMME 120 in order to inform the MME 120 that the creation of the NASsecurity key is completed (S226).

In order to inform the HSS 130 of the attachment of the terminal 100 andrequest the HSS to transmit subscription information, the MME 120transmits an update location request message to the HSS 130 (S227).

The HSS 130 transmits the user subscription information to the MME 120through an update location response message (S228).

Next, the MME 120 transmits a create session request message to the P-GW140 (S229) in order to perform a session request.

The P-GW 140 receiving the create session request message allocates anIP address of the terminal 100 (S230). The P-GW 140 allows the allocatedIP address to be included in a create session response message, andtransmits the create session response message including the allocated IPaddress to the MME 120 (S231).

The MME 120 transmits an attach accept message to the terminal 100(S232). Here, the attach accept message includes the IP address of theterminal 100 allocated by the P-GW 140.

A tunnel is finally created between the P-GW 140 and the ePDG 160depending on the procedure described above (S223), and data transmissionand reception are performed among the P-GW 140, the ePDG 160, and theterminal 100 through such a tunnel. That is, the NAS protocol is alsoapplied to the non-3GPP access network N2 through the proceduresdescribed above, such that mobility management may be performed.

Meanwhile, even in the case in which the terminal 100 is connected tothe base station 110 rather than the ePDG 160, the same procedures asthose described above with reference to FIG. 2 are performed, such thatNAS communication based on an IP instead of a radio resource control(RRC) may be performed. Therefore, according to an exemplary embodimentof the present invention, the NAS protocol may be applied on the basisof IP communication regardless of a kind of terminal interface (LTE,WiFi, wired, or the like).

FIG. 3 is a view showing a protocol stack of a control plane forapplying the NAS based access method according to an exemplaryembodiment of the present invention.

As shown in FIG. 3, an NAS stratum 310 is positioned on an IP stratum320 in the terminal 100, and an NAS stratum 330 is positioned on an IPstratum 340 also in the MME 120. That is, the NAS protocol is usedbetween the terminal 100 and the MME 120. In addition, each of theterminal 100 and the MME 120 performs the IP communication with the ePDG160. Therefore, according to an exemplary embodiment of the presentinvention, an NAS message may be transferred in a state in which it iscarried in the IP stratum.

FIG. 4 is a view showing an NAS based access method according to anotherexemplary embodiment of the present invention. In more detail, FIG. 4shows procedures of applying the NAS protocol in an untrusted WiFiaccess network environment to allow the terminal 100 to initially accessthe core network.

As shown in FIG. 4, the NAS based access method according to anotherexemplary embodiment of the present invention is the same as thatillustrated in FIG. 2 except that a process (S600) of creating an IPSectunnel is added.

In order to perform authentication and negotiation between the terminal100 and the ePDG 160, an Internet key exchange (IKE) securityassociation (SA) process is performed. In such an IKE SA process, amaster key is created, such that an IKE message is encrypted, and anencryption integrity algorithm negotiation and session key is created.Next, an IPSec SA is configured between the terminal 100 and the ePDG160. The IPSec SA includes a key, an algorithm, and the like, used forencrypting and authenticating a packet. The IPSec SA is configured,security communication may be performed between the terminal 100 and theePDG 160 through an IPSec tunnel.

Since procedures of FIG. 4 are the same as those of FIG. 2 except forS600, a detailed description therefor will be omitted. That is, in theNAS based access method according to another exemplary embodiment of thepresent invention, the NAS protocol may be applied between the terminal100 and the MME 120 through the IPSec tunnel created in S600.

FIG. 5 is a view showing a protocol stack of a control plane forapplying the NAS based access method according to another exemplaryembodiment of the present invention.

As shown in FIG. 5, an IPSec tunnel 510 is created between the terminal100 and the ePDG 160, such that security may be provided. According toanother exemplary embodiment of the present invention described above,the NAS message may be transferred in a state in which it is carried inan IP to which the security is added.

FIG. 6 is a view showing a protocol stack of a data plane for applyingthe NAS based access method according to an exemplary embodiment of thepresent invention.

As shown in FIG. 6, communication may be performed between the terminal100 and the P-GW 140 using the IP address 610 allocated by the P-GW 140in S230 of FIG. 2. In addition, a temporary IP 630 may be used in IPcommunication for data communication between the terminal 100 and theePDG 160, and an IPsec tunnel 620 may be used for safe communication. Ageneric routing encapsulation (GRE) tunnel 640 may be used in the datacommunication between the ePDG 160 and the P-GW 140.

FIG. 7 is a view showing another example of a protocol stack of acontrol plane for applying the NAS based access method according to anexemplary embodiment of the present invention. That is, FIG. 7 shows acase in which a general packet radio service (GPRS) tunneling protocol(GTP) tunnel is used instead of a GRE tunnel.

As shown in FIG. 7, an NAS protocol is performed on the basis of IPcommunication between the terminal 100 and the ePDG 160, and an NASmessage may be transferred through a GTP-C protocol 720 between the ePDG160 and the MME 120.

In FIGS. 2 to 7, the case in which the NAS message is transferredthrough the IP communication between the terminal 100 and the ePDG 160has been shown. The NAS message may be transmitted through a 801.11media access control (MAC) frame between the terminal 100 and the ePDG160, in addition to such a method. Such a method will be described withreference to FIGS. 8 and 9.

FIG. 8 is a view showing a protocol stack of a control plane forapplying an NAS based access method according to yet another exemplaryembodiment of the present invention. That is, FIG. 8 shows a case inwhich an NAS message is transmitted through an MAC frame in an Ethernetnetwork in which an IP is not supported.

As shown in FIG. 8, an NAS stratum 810 is positioned on an MAC stratum820 in the terminal 100, and an NAS stratum 840 is positioned on an IPstratum 830 in the MME 120. MAC communication is performed between theterminal 100 and the ePDG 160, and IP communication is performed betweenthe ePDG 160 and the MME 120. In addition, an NAS protocol is usedbetween the terminal 100 and the MME 120. Therefore, according to yetanother exemplary embodiment of the present invention, an NAS message istransmitted through the MAC communication between the terminal 100 andthe ePDG 160.

There may be two methods for transmitting the NAS message between theterminal 100 and the ePDG 160. A first method is a method of newlyadding Ether_Type to an Ethernet frame. In addition, a second method isa method of using a specific MAC address. According to yet anotherexemplary embodiment of the present invention as described above, theMAC frame may be used as it is without using the IP communication, inorder to transfer the NAS message between the terminal 100 and the ePDG160. Here, the well-known values defined as standards may be used as theEther_Type or the specific MAC address or values defined with respect toeach other as private values in a network may be used as the Ether_Typeor the specific MAC address.

FIG. 9 is a view showing a protocol stack of a data plane for applyingthe NAS based access method according to yet another exemplaryembodiment of the present invention.

As shown in FIG. 9, an IP stratum 910 is positioned on an MAC stratum920 in the terminal 100. That is, IP communication 910 may be used on anEthernet frame 920 as it is. In addition, data communication between theterminal 100 and the ePDG 160 is performed through MAC communication 920rather than the IP communication. Data communication between theterminal 100 and the P-GW 140 is performed through the IP communication910.

FIG. 10 is a view showing a terminal 100 according to an exemplaryembodiment of the present invention.

As shown in FIG. 10, the terminal 100 according to an exemplaryembodiment of the present invention includes a processor 101, a memory102, and a radio frequency (RF) module 103.

The processor 101 is designed to implement the methods and the protocolstacks in FIGS. 1 to 9.

The memory 102 is connected to the processor 101, and stores variouskinds of information related to operations of the processor 101 therein.

The RF module 103 is connected to an antenna (not shown), and transmitsor receives wireless signals. In addition, the antenna may beimplemented by a single antenna or a multi-antenna (a multi-inputmulti-output (MIMO) antenna).

According to the exemplary embodiments of the present inventiondescribed above, the NAS protocol is applied to the non-3GPP accessnetwork, thereby making it possible to provide the seamless handover aswell as provide the mobility regardless of the access network.

Although the exemplary embodiment of the present invention has beendescribed in detail hereinabove, the scope of the present invention isnot limited thereto. That is, several modifications and alterations madeby a person of ordinary skill in the art using a basic concept of thepresent invention as defined in the claims fall within the scope of thepresent invention.

What is claimed is:
 1. A method for accessing a core network through anon-3^(rd) generation partnership project (3GPP) access network by aterminal, the method comprising: receiving an Internet protocol (IP)address of the terminal from a first gateway included in the non-3GPPaccess network, wherein the IP address is allocated by the firstgateway; and transmitting a non-access stratum (NAS) message to a firstdevice managing mobility of the terminal via the first gateway by usingthe IP address, wherein the first gateway and the first device aredirectly connected to each other without any other gateway.
 2. Themethod of claim 1, wherein the receiving of the IP address allocatedfrom the first gateway includes receiving a temporary IP addressallocated from the first gateway.
 3. The method of claim 2, wherein thenon-3GPP access network is a wireless local area network (WLAN).
 4. Themethod of claim 2, wherein the receiving of the temporary IP addressallocated from the first gateway includes receiving the temporary IPaddress allocated from the first gateway through an IPv6auto-configuration method or a dynamic host configuration protocol(DHCP) method.
 5. The method of claim 1, wherein the receiving of the IPaddress allocated from the first gateway includes creating an Internetprotocol security (IPSec) with the first gateway.
 6. The method of claim5, wherein the non-3GPP access network is an untrusted non-3GPP accessnetwork.
 7. The method of claim 5, wherein the creating of the IPSectunnel includes: performing an Internet key exchange (IKE) securityassociation (SA) process together with the first gateway; and performingan IPSec security association (SA) process together with the firstgateway.
 8. The method of claim 1, wherein the transmitting of the NASmessage includes: receiving a security mode command message from thefirst device through the IP address; and transmitting a security modecomplete message to the first device through the IP address.
 9. Themethod of claim 8, wherein the transmitting of the NAS protocol furtherincludes receiving an attach accept message from the first devicethrough the IP address.
 10. A terminal initially accessing a corenetwork through a non-3GPP access network, the terminal comprising: aprocessor performing a control to receive an IP address of the terminalfrom a first gateway included in the non-3GPP access network andperforming a control to transmit an NAS message to a first devicemanaging mobility of the terminal via the first gateway by using the IPaddress, wherein the IP address is allocated by the first gateway; and aradio frequency (RF) module transmitting and receiving a messagecorresponding to the NAS protocol, wherein the first gateway and thefirst device are directly connected to each other without any othergateway.
 11. The terminal of claim 10, wherein the IP address is atemporary IP address allocated from the first gateway.
 12. The terminalof claim 10, wherein the IP address is a temporary IP address allocatedfrom the first gateway by creating an IPSec with the first gateway. 13.The terminal of claim 10, wherein the processor configures an NASstratum to be positioned on an IP stratum.
 14. The terminal of claim 10,wherein the first gateway is a non-3GPP interworking function and thefirst device is an access and mobility management function.
 15. Themethod of claim 1, wherein the first gateway is a non-3GPP interworkingfunction and the first device is an access and mobility managementfunction.